J. Chem. Eng. Data 1997, 42, 897-899
897
Densities of Carbon Dioxide + Methane Mixtures from 225 K to 350 K at Pressures up to 35 MPa Chih-An Hwang, Gustavo A. Iglesias-Silva,† James C. Holste, and Kenneth R. Hall* Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122
Bruce E. Gammon and Kenneth N. Marsh‡ Thermodynamics Research Center, Texas Engineering Experiment Station, College Station, Texas 77843-3111
This paper reports PVT measurements for five gravimetrically prepared CO2 + CH4 mixtures. A continuously-weighed, high-pressure pycnometer was used to measure densities at temperatures from 225 K to 350 K in 25 K increments and pressures to 35 MPa with one set of measurements to 69 MPa. A detailed error analysis indicates that the accuracy of the densities is better than (0.1%.
Introduction This paper reports experimental density measurements for CO2 + CH4 mixtures at temperatures from 225 K to 350 K and pressures up to 35 MPa (one isotherm up to 69 MPa). Brugge et al. (1989) report Burnett data and virial coefficients at 300 K and 320 K. Esper et al. (1989) report Burnett-isochoric measurements from 205 K to 320 K and pressures from 0.1 MPa to 48 MPa. Standard thermodynamic procedures permit evaluation of other properties from the densities. GPA/GRI Research Report RR-138 authored by Hwang et al. (1995) contains: energies (internal, Helmholtz, and Gibbs), enthalpies, and entropies obtained from the data reduction method described by Duarte-Garza et al. (1997); second and third virial coefficients for both the pure compounds and the mixture. Additional PVT data for CO2 + CH4 mixtures have been measured by Netherlandse Gasunie, and Ruhrgas as reported by Jaeschke and Humphreys (1990). Experimental Section Materials. The carbon dioxide was Ultra Pure grade from Scientific Gas Products, Inc., with a purity better than 99.995 mol % with 40 ppm nitrogen and 40 ppm oxygen maximum. The sample was degassed by pumping with a vacuum over a frozen sample for a least 30 min. The methane was Ultra Pure grade from Scientific Gas Products, Inc., with a specified purity of better than 99.995 mol % with nitrogen as the principal impurity. Additional purification was not attempted for the methane. Measurements. The data were measured using a pycnometer that consisted of a sample cell of known volume suspended from an electronic balance described in detail * Corresponding author. †Present address: Dept. Ingenierı´a Quimica, Inst. Tecnolo ´ gico de Celaya, Celaya, Guanajuato, CP 38010 Mexico. ‡ Present address: Department of Chemical and Process Engineering, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
S0021-9568(97)00042-3 CCC: $14.00
by Lau (1986) and Lau et al. (1997). Pressures were measured using pressure transducers that were calibrated in-situ against an automatic dead-weight gauge pressure standard. The accuracy of the pressure measurements was estimated to be (0.006 MPa. Temperatures were measured with a four-lead platinum resistance thermometer that was adjacent to the sample cell on the inside surface of the compartment. The temperature was controlled to (0.002 K and measured to an accuracy of (0.005 K on ITS90; thus, the even values reported in the table are correct within experimental error. The mole fractions of the mixtures, which were prepared gravimetrically, were accurate to (0.000 05 excluding any effects of sample impurity. The uncertainties in the pycnometric density measurements arose from the uncertainties in the mass determinations and from the cell volume calibration. The error in the cell volume calibrations was about (0.04%, which includes random errors introduced by uncertainties in the temperature and pressure measurements, uncertainties from using a calibrating fluid, and errors associated with mass determinations. The estimated accuracy (at 95% confidence limit) provided by Lau et al. (1997) in the pycnometric density measurements is
∆F ) {(0.15)2 + (0.0004F)2}1/2; F in kg‚m-3 or
∆F/F ) [{0.15/F}2 + 1.6 × 10-7]1/2; F in kg‚m-3 Results and Conclusions Table 1 contains densities and derived compression factors for four CO2 + CH4 mixtures measured at temperatures from 225 K to 450 K at pressures up to 35 MPa (with one isotherm to 69 MPa). The experimental values are state-of-the-art and generally accurate within (0.1%. These results are suitable for both stringent testing and development of models and correlations and formed a significant contribution to the development of the American Gas Association Standard AGA-8. © 1997 American Chemical Society
898 Journal of Chemical and Engineering Data, Vol. 42, No. 5, 1997 Table 1. Experimental PVT Values for CO2 (A) + CH4 (B) Mixtures Determined Using the Pycnometer. Mr,A ) 44.010, Mr,B ) 16.043 p/MPa
F/mol‚m-3
Z
p/MPa
F/mol‚m-3
Z
p/MPa
F/mol‚m-3
32.234 27.431 21.910
19 839 19 121 18 061
0.8685 0.7669 0.6485
17.116 13.043 10.222
34.040 29.987 26.205 22.724
18 132 17 403 16 576 15 614
0.9032 0.8290 0.7606 0.7002
19.265 16.544 13.751
x(CO2) ) 0.09826, Mr ) 18.791 T ) 225.00 K 16 719 0.5472 8.504 9 586 14 865 0.4691 6.785 6 208 12 410 0.4403 T ) 250.00 K 14 369 0.6450 11.673 9 262 13 039 0.6104 9.606 7 116 11 138 0.5940 7.554 5 068
34.350 30.397 26.245
16 312 15 466 14 362
0.9210 0.8596 0.7992
22.103 17.963 14.546
12 940 11 029 8 970
69.471 62.575 55.680
19 899 19 291 18 590
1.4544 1.3514 1.2478
48.784 41.886 34.793
17 764 16 775 15 520
34.350 30.414 26.275 22.818
14 607 13 653 12 441 11 220
0.9428 0.8931 0.8467 0.8153
19.370 16.602 13.864
32.059 28.363 24.851
11 300 10 308 9 247
0.9749 0.9455 0.9235
21.405 17.955 15.260
Z
p/MPa
F/mol‚m-3
Z
0.4742 0.5842
5.020 2.790
3 776 1 758
0.7107 0.8486
0.6063 0.6494 0.7171
6.150 4.067 1.827
3 843 2 306 941
0.7699 0.8486 0.9345
6 988 5 036
0.7335 0.7789
6.206 4.132
3 230 2 024
0.8403 0.8928
13 844 11 408
0.8454 0.7743
14.307 6.3116
7 819 3 040
0.7623 0.8649
9 758 8 403 6 940
T ) 275.00 K 0.7471 11.719 0.7123 8.970 0.7092 T ) 288.71 K 1.1440 28.093 1.0402 21.203 0.9339 T ) 300.00 K 0.7958 11.789 0.7921 9.714 0.8009 7.645
5 793 4 645 3 536
0.8159 0.8385 0.8668
6.262 4.191 2.117
2 825 1 819 883
0.8886 0.9238 0.9615
8 095 6 845 5 819
T ) 350.00 K 0.9087 12.479 0.9014 9.727 0.9011
4 728 3 634
0.9071 0.9198
6.948 4.211
2 546 1 507
0.9379 0.9606
17 571
0.3999
9.946
16 016
0.3320
9 984 7 939 5 878
0.5424 0.5809 0.6466
6.806 5.427 3.341
4 442 3 254 1 785
0.7088 0.7716 0.8659
9 257 7 571 5 831
0.6398 0.6651 0.7098
7.449 6.141 4.100
4 152 3 253 2 013
0.7707 0.8110 0.8750
4 633 3 738
0.8761 0.8920
7.657 6.259
2 889 2 324
0.9109 0.9254
x(CO2) ) 0.298 58, Mr ) 24.393 T ) 300.00 K 14 021 0.7894 17.297 9 756 12 892 0.7511 13.937 7 707 11 503 0.7226 10.373 5 389
0.7108 0.7250 0.7716
7.557 5.557 3.323
3 661 2 554 1 441
0.8275 0.8723 0.9245
0.3049 0.2126
6.866
21 883
0.1677
0.3577 0.2879
8.886 7.507
18 760 18 165
0.2279 0.1988
0.3331 0.3454
8.702 8.016
10 303 8 331
0.3694 0.4208
0.5198 0.5792 0.6544
6.600 4.189 2.112
3 590 1 994 916
0.7371 0.8424 0.9244
0.7692 0.8163 0.8594
4.562 2.153
1 726 772
0.9081 0.9579
x(CO2) ) 0.291 09, Mr ) 24.184 31.914 26.877
21 076 20 450
0.8094 0.7025
22.054 17.116
19 724 18 729
34.401 30.357 26.142 22.697
18 686 18 015 17 155 16 260
0.8516 0.7795 0.7049 0.6457
19.255 16.503 13.731
15 090 13 804 11 929
34.339 30.391 26.178
17 122 16 333 15 285
0.8615 0.7993 0.7357
22.739 19.294 16.551
14 179 12 732 11 218
34.545 30.402 26.263
12 590 11 532 10 297
0.9429 0.9059 0.8765
22.797 19.362 13.844
9 108 7 803 5 502
40.704 37.915 34.470 30.972
16 868 16 391 15 724 14 927
0.9674 0.9274 0.8789 0.8318
27.606 24.151 20.733
T ) 225.00 K 0.5977 13.145 0.4885 T ) 260.00 K 0.5903 11.706 0.5530 9.970 0.5325 8.216 T ) 280.00 K 0.6889 13.787 0.6509 11.722 0.6338 9.636 T ) 350.00 K 0.8601 11.812 0.8527 9.703 0.8647
32.507 27.380
24 296 23 947
0.7152 0.6112
22.569 16.979
34.161 29.577
22 624 22 211
0.7264 0.6406
24.745 19.956
34.352 29.654 24.855
20 711 20 125 19 388
0.7254 0.6444 0.5607
19.974 15.885 12.466
34.390 30.405 26.238 22.749
18 667 17 997 17 122 16 183
0.7386 0.6773 0.6144 0.5636
19.333 16.601 13.903
x(CO2) ) 0.668 16, Mr ) 34.729 T ) 225.00 K 23 585 0.5115 12.926 22 665 23 089 0.3931 8.809 22 146 T ) 250.00 K 21 712 0.5483 15.127 20 347 21 114 0.4547 11.741 19 623 T ) 275.00 K 18 402 0.4747 10.404 13 659 17 215 0.4036 9.300 11 775 15 564 0.3503 T ) 300.00 K 14 939 0.5188 11.783 9 088 13 525 0.4921 10.076 6 975 11 433 0.4875 8.364 5 124
34.268 29.650 24.834
14 789 13 586 11 968
0.7963 0.7500 0.7131
20.737 17.308 14.558
10 194 8 406 6 844
T ) 350.00 K 0.6990 11.797 0.7076 9.153 0.7310 6.975
5 270 3 853 2 789
Journal of Chemical and Engineering Data, Vol. 42, No. 5, 1997 899 Table 1. (Continued) p/MPa
F/mol‚m-3
Z
p/MPa
F/mol‚m-3
Z
p/MPa
F/mol‚m-3
Z
p/MPa
F/mol‚m-3
Z
x(CO2) ) 0.901 12, Mr ) 41.244 37.871 32.445 27.618
26 742 26 522 26 312
0.7570 0.6539 0.5611
22.618 17.680
26 077 25 829
T ) 225.00 K 0.4636 12.884 0.3659 9.422
25 567 25 357
0.2694 0.1986
6.194 3.211
25 149 24 942
0.1317 0.0688
31.317 26.251 21.472
24 701 24 393 24 070
0.6099 0.5177 0.4292
17.016 13.073
23 735 23 396
T ) 250.00 K 0.3449 9.831 0.2688 7.873
23 083 22 869
0.2049 0.1656
6.101 4.490
22 661 22 447
0.1295 0.0962
41.684 35.202 29.718
23 580 23 139 22 704
0.7731 0.6654 0.5725
24.576 20.383 16.736
22 232 21 784 21 323
T ) 275.00 K 0.4835 13.214 0.4092 9.443 0.3433
20 774 20 016
0.2782 0.2063
7.659 6.233
19 520 19 009
0.1716 0.1434
41.333 37.955 34.558 30.354 26.307
21 773 21 468 21 124 20 642 20 100
0.7611 0.7088 0.6559 0.5895 0.5247
21.973 17.911 13.751 10.916
19 382 18 513 17 139 15 402
T ) 300.00 K 0.4545 9.363 0.3879 8.667 0.3217 8.200 0.2842 7.789
13 127 10 655 8 348 6 770
0.2860 0.3261 0.3938 0.4613
7.357 6.771 5.726 4.024
5 660 4 621 3 379 2 028
0.5212 0.5874 0.6794 0.7955
44.924 39.439 34.474 29.632
18 656 17 877 17 013 15 941
0.8275 0.7581 0.6963 0.6388
29.500 24.978 21.537 18.031
15 902 14 551 13 112 11 065
T ) 350.00 K 0.6375 15.418 0.5899 13.568 0.5645 11.381 0.5600
9 094 7 558 5 816
0.5826 0.6169 0.6725
9.631 7.478 4.700
4 570 3 263 1 856
0.7242 0.7876 0.8704
Literature Cited Brugge, H. B.; Hwang, C.-A.; Rogers, W. J.; Holste, J. C.; Hall, K. R. Experimental cross virial coefficients for binary mixtures of carbon dioxide with nitrogen, methane and ethane at 300 and 320 K. Physica 1989, A156, 382-416. Duarte-Garza, H.; Holste, J. C.; Hall, K. R.; Iglesias-Silva, G. A. A technique for preparing thermodynamic property tables using incomplete data sets. Fluid Phase Equilib. 1997, in press. Esper, G. J.; Bailey, D. M.; Holste, J. C.; Hall, K. R. Volumetric behavior of near-equimolar mixtures of carbon dioxide + methane and carbon dioxide + nitrogen. Fluid Phase Equilib. 1989, 49, 3547 Hwang, C.-A.; Duarte-Garza, H. A.; Eubank, P. T.; Holste, J. C.; Hall, K. R.; Gammon, B. E.; Marsh, K. N. Gas Processors Association/ Gas Research Institute Research Report RR-138, 1995. Jaeschke, M.; Humphreys, A. E. GERG Technical Monograph 4, The GERG Databank of High Accuracy Compressibility Factor Measure-
ments; Verlag des Vereins Deutscher Ingenieure: Dusseldorf, Germany, 1990. Lau, W.-W. R. A Continuously Weighed Pycnometer Providing Densities for Carbon Dioxide + Ethane Mixtures Between 240 and 350 K at Pressures Up to 35 MPa. Ph.D. Dissertation, Texas A&M University, College Station, TX, 1986. Lau, W. R.; Hwang, C.-A.; Brugge, H. B.; Iglesias-Silva, G. A.; DuarteGarza, H. A.; Rogers, W. J.; Hall, K. R.; Holste, J. C.; Gammon, B. E.; Marsh, K. N. A continuously weighed pycnometer for measuring fluid properties. J. Chem. Eng. Data 1997, 42, 738-744. Received for review February 16, 1997. Accepted May 21, 1997.X The authors acknowledge financial support from the Gas Research Institute, the Gas Processors Association, and the Texas Engineering Experiment Station.
JE970042B X
Abstract published in Advance ACS Abstracts, July 1, 1997.
